1. Field of the Invention
The present invention relates to a treatment of polymeric materials and more particularly to treating a portion of a surface of a polymeric material with radiation to minimize the effect of a subsequent chemical etching treatment, the radiation thus acting as a masking agent.
2. Description of Related Art
There are many applications for bonding articles to polymeric materials. Many of those applications require bonding to selected portions of the polymeric materials. For example, in surface mounted components, which are merely mounted on top of printed wiring boards (PWB), or soft substrate PWB'S, which have all components attached to a soft polymeric substrate, it is necessary to pattern select areas on the printed wiring boards for adhesive attachment. Another application concerns the encapsulation of electronic devices which contain wires insulated by a polymeric material. In such devices, for stress relief of the wires, it is necessary that the wire coating not adhere to the encapsulation material except in areas immediately adjacent to the electronic components. Adhesion over the length of the connecting wires would create stress on the components and would result in high failure rates.
Due to the chemical inertness of many polymeric materials, such as polytetrafluoroethylene (PTFE), it is frequently difficult to provide adequate adhesion. A standard industrial process for improving adhesion of polymeric materials involves chemically etching the surface of the material with a commercially available sodium-containing solution (such as Tetra-Etch (TM), sold by W.L. Gore & Associates) to prepare the surfaces of such materials for adhesion. Chemical etching greatly modifies properties of the material, for example, color, wettability and surface resistance. The etching process produces a highly porous surface, the chemical attack extending to depths up to 10,000 .ANG..
Selective etching has been accomplished by masking the surface being etched with materials that are both water-tight and chemically impervious to the etching solution.